Flat heating surface type gas stove

ABSTRACT

There is disclosed a novel flat heating surface type gas stove which is capable of heating a heating substance across a heat resistance glass at practically applicable heating efficiency, overcoming any inconvenience resulting from the exposure of flame and facilitating the cleaning of the gas stove. This gas stove  10  comprises a heat resistance glass top plate  12  which is disposed over a burner  15,  wherein a gas-permeable porous body  40  is disposed below said top plate  12,  and a space between said top plate  12  and a surface of said gas-permeable porous body  40  is assigned to a combustion space S. Combustion gas generated is designed to be discharged through said gas-permeable porous body  40.  As high-temperature combustion gas passes through said gas-permeable porous body  40,  radiant heat B is generated from the surface of said gas-permeable porous body  40.  Since the heating substance  4  is heated by both of heat conduction and radiation, high heating efficiency can be achieved.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a gas stove which is adapted forcooking in office or home, and in particular, to a flat heating surfacetype gas stove wherein a heat-resisting glass top plate is used as aflat heating surface, thereby preventing flame from being exposed out ofthe heating surface during the heating operation thereof.

[0003] 2. Description of the Related Art

[0004] The conventional gas stove is generally designed such that aheating substance (i.e. substance to be heated) is directly heated bycombustion gas (including flame) that is generated by the combustion ofgas. Specifically, as shown in FIG. 5, a heating substance 4, such as apot or a frying pan (skillet), which is supported by means of a pansupport 3 is placed over the combustion burner 2 that is exposed out ofthe top plate 1 of the stove. In the case of a conventional stove ofthis type, since the burner and the pan support are exposed, the stoveis required to be frequently cleaned, and at the same time, since thesurface structure thereof is rather complicated, it is difficult tocompletely sweep away soils from the surface of stove. Additionally,since flame is exposed during heating, radiant heat is transmitteddirectly to a person using the stove, thus occasionally imparting afeeling of heat to the person. Therefore, the person using the stove isrequired to pay some degree of attention to ensure safety in dealingwith the stove.

[0005] With a view to avoiding such an inconvenience, there has beenproposed an electric stove as shown in FIG. 6, which is constructed, asrepresented by an IH stove, a halogen stove or a radiant heat stove,such that the top plate 5 of stove is constituted by heat resistantglass such as ceramic glass, and that the heating substance 4 is heatedby means of electromagnetic wave (including visible light and infraredray) which is designed to pass through this glass top plate 5 as it isgenerated from a heater 6.

[0006] It is now studied for enabling the same heating method asemployed in the aforementioned electric stove to be realized in a gasstove where gas is employed as a fuel. However, since only the visiblelight and infrared ray to be generated through the combustion of gas canbe utilized in heating a heating substance instead of directly utilizingthe combustion gas if the aforementioned method is adopted in a gasstove, the heating efficiency of such a gas stove would greatlydeteriorate even if the gas stove is of an infrared burner type. Namely,it has been considered very difficult in such a gas stove to improve theheating efficiency thereof to a practically applicable level.

[0007] The present invention has been accomplished under thecircumstances explained above, and therefore, an object of thisinvention is to provide a novel flat heating surface type gas stovewhich is capable of heating a heating substance across a heat resistanceglass at such high heating efficiency that is applicable to practicaluse in spite of the fact that the gas stove employs gas as a fuel, thusmaking it possible to overcome any inconvenience that may be broughtabout due to the exposure of flame, and to facilitate the cleaning ofthe gas stove.

BRIEF SUMMARY OF THE INVENTION

[0008] Namely, the gas stove according to the present invention is aflat heating surface type gas stove, which fundamentally comprises aheat resistance glass top plate which is disposed over a burner, whereina gas-permeable porous body is disposed below said top plate, a spacebetween said top plate and a surface of said gas-permeable porous bodyis assigned to a combustion space, and combustion gas to be generated isdesigned to be discharged through said gas-permeable porous body.

[0009] It is known that when a high-temperature gas is passed through agas-permeable porous body, thermal energy is transferred from thehigh-temperature gas to the porous body and is then radiated from thesurface of the porous body (“The improvements on the combustion andradiant heat in porous solid body”, a collection of articles 52-475,B-1136; Japan Society of Mechanical Engineers). By increasing theporosity of porous body, or by employing a material of high emissivityas a porous body, the radiation from the porous body can be increased,thus lowering the temperature of porous body and rapidly lowering thetemperature of gas. As a high-temperature gas is passed through agas-permeable porous body, even though the temperature of gas on the gasinlet side of the porous body is high, the temperature of gas on the gasoutlet side of the porous body becomes low. Therefore, the radiationfrom the porous body can be effected selectively on the high-temperaturegas side, i.e. the upstream side of gas.

[0010] According to the present invention, the flat heating surface typegas stove which is provided with a heat resistance glass top platedisposed over a burner is technically featured in that theaforementioned phenomenon to be realized by the gas-permeable porousbody is effectively utilized. Therefore, it is now possible to obtain aflat heating surface type gas stove which is capable of exhibiting suchhigh-heating efficiency that can be practically used in spite of thefact that the gas stove employs gas as a fuel.

[0011] Namely, in the case of the gas stove according to the presentinvention, the combustion heat from the burner is transmitted to aheating substance by two ways, i.e. by the energy of heat conductionoriginating directly from the heat resistant glass top plate (flatheating surface) and by the radiation energy originating from thesurface of gas-permeable porous body, that can be generated as thecombustion gas of high-temperature produced inside the combustionchamber is permitted to pass through the gas-permeable porous body whichis disposed below the top plate, the combustion gas entering thegas-permeable porous body from the top surface thereof and dischargedfrom the rear surface thereof. As a result, it is now possible, withthis gas stove, to realize high heating efficiency.

[0012] Moreover, in the gas stove according to the present invention,since the surface to support and heat a heating substance, such as a potor a frying pan, is flat, the cleaning can be easily performed even ifthis surface is soiled by boiled-over matter. Additionally, since thecombustion space of this gas stove is substantially closed so that theflame of combustion gas is not permitted to expose out of the combustionspace, it is possible to ensure a high operational safety.

[0013] As for the material of gas-permeable porous body which enablesthe aforementioned combustion gas to pass therethrough, there is not anyparticular limitation as long as it has a predetermined heat resistance.However, it is more preferable that the material of gas-permeable porousbody is capable of emitting a higher radiation toward the upstream sideas a high-temperature gas is passed therethrough. Preferable examples ofsuch a gas-permeable porous body are those which are formed into aporous body by making use of silicon carbide exhibiting a highemissivity (0.9 or more) or a material containing silicon carbide as amain component. For example, an aggregate of silicon carbide fibers orceramic filters can be preferably employed as the material ofgas-permeable porous body.

[0014] The surface of gas-permeable porous body is heated up to almostthe same temperature as that of the combustion gas as thehigh-temperature combustion gas passes through the gas-permeable porousbody, thereby radiating thermal energy. In the course of the passage ofcombustion gas across the gas-permeable porous body, the temperature ofcombustion gas is lowered to become a low temperature gas, which is thendischarged out of the gas stove. Even this low temperature gas, thetemperature thereof is maintained generally at 600° C. or so. Therefore,heat radiation is caused to generate even on the gas outlet side, i.e.rear side of the gas-permeable porous body, the heat radiation thusgenerated being directed toward the exhaust side of the gas stove, thusresulting in a heat loss to the gas stove.

[0015] With a view to minimize this heat loss, there is provided anotherembodiment of gas-permeable porous body wherein a second gas-permeableporous body having a lower emissivity than that of the first mentionedgas-permeable porous body is laminated on the gas outlet side of thefirst mentioned gas-permeable porous body. As for the material of thesecond gas-permeable porous body also, there is not any particularlimitation as long as it has a predetermined heat resistance. However,it is more preferable that the material of the second gas-permeableporous body is formed of silica/alumina-based ceramic exhibiting anemissivity ranging from 0.2 to 0.3 or a material containing as a maincomponent such a silica/alumina-based ceramic. For example, an aggregateof silica/alumina-based ceramic fiber can be preferably employed.Alternatively, a ceramic filter exhibiting a relatively low emissivitycan be employed as the second gas-permeable porous body.

[0016] According to the flat heating surface type gas stove of thepresent invention, there is not any particular limitation with regard tothe burner to be employed therein. For example, the burner may be a pipeburner which is disposed to surround a region immediately above thegas-permeable porous body or a surface combustion type burner. In thecase of the former burner, the flame ports thereof are preferablydisposed in such a manner that the flame from each flame port can behorizontally ejected in the direction toward the center of the regionimmediately above the gas-permeable porous body. If a sufficientcombustion of gas can be achieved with only a primary air, thearrangement of the burner maybe such as mentioned above. Generallyhowever, when it is desired to achieve a desired combustion of gas withonly a primary air, the blow-off of flame or the generation of unburntgas is caused to occur. In order to prevent such phenomena, the burnershould preferably be designed such that a secondary combustion air canbe supplied from the vicinity of each of the flame ports. In any cases,it is preferable to provide the burner with a suitable flame stabilizingmechanism.

[0017] In a structure where a surface combustion burner is employed, thecombustion surface thereof, together with the surface of gas-permeableporous body, is disposed so as to face the combustion space. As aresult, the combustion heat of the surface combustion burner can beeffectively conducted to the flat heating surface constituted by theheat resistant glass top plate. Preferably, the combustion surface ofthe surface combustion burner should be formed of a material exhibitinga high emissivity, such as silicon carbide or a material containingsilicon carbide as a main component. In this case, in addition to theheating by way of heat conduction, the heating by way of radiationenergy can be proceeded, thereby making it possible to realize highheating efficiency by the surface combustion burner.

[0018] If the surface combustion burner is to be employed, thecombustion surface thereof may be disposed on the periphery of thesurface of the gas-permeable porous body, or the gas-permeable porousbody may be disposed on the periphery of the combustion surface of thesurface combustion burner. In any cases, a high-temperature combustiongas from the surface combustion burner is permitted to be dischargedthrough the gas-permeable porous body, during which the gas-permeableporous body is heated to a red heat state, thus radiating thermalenergy.

[0019] According to another embodiment of the gas stove of the presentinvention, the gas stove essentially comprises a combustion gaspassageway communicated with a space located on a downstream side ofcombustion gas flow channel of gas-permeable porous body; an airpassageway for combustion, and a heat-exchanging means to be actedbetween the combustion gas passageway and the air passageway forcombustion, wherein a mixed gas comprising a combustion gas andcombustion air which has been heated through heat exchange thereof withthe combustion gas by means of heat-exchanging means is designed to befed to a burner. In the case of gas stove of this embodiment, thequantity of heat retained in the combustion gas after the passagethereof through the gas-permeable porous body is transferred via theheat-exchanging means to the combustion air to thereby perform exhaustheat recovery. As a result, the air thus heated up and the combustiongas is enabled to be mixed together to form a mixed gas, which is thentransferred to the burner for the combustion thereof, resulting inimproved heating efficiency as a whole.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0020]FIG. 1 is a cross-sectional view illustrating one embodiment ofthe flat heating surface type gas stove of the present invention;

[0021]FIG. 2 is a cross-sectional view illustrating another embodimentof the flat heating surface type gas stove of the present invention;

[0022]FIG. 3 is a cross-sectional view illustrating a further embodimentof the flat heating surface type gas stove of the present invention;

[0023]FIG. 4 is a cross-sectional view illustrating still anotherembodiment of the flat heating surface type gas stove of the presentinvention;

[0024]FIG. 5 is a side view schematically illustrating one example ofconventional gas stove; and

[0025]FIG. 6 is a side view schematically illustrating one example ofconventional radiation type stove where an electric heater is disposed.

DETAILED DESCRIPTION OF THE INVENTION

[0026] Next, the flat heating surface type gas stove according to thisinvention will be explained with reference to specific embodiments.

[0027]FIG. 1 shows a cross-sectional view of one embodiment of the flatheating surface type gas stove according to this invention. The gasstove 10 shown in FIG. 1 is of a closed type wherein the open top faceof an outer casing 11 having a cylindrical configuration is closed by aflat heat resistant glass top plate. A ring-like pipe burner 15 isdisposed along an upper inner wall portion of the outer casing 11. Thepipe burner 15 is provided with a plurality of flame ports 16 which aredisposed at predetermined intervals in such a manner that each flameport 16 is directed so as to enable the flame to be ejected horizontallytoward the center of the outer casing 11. The pipe burner 15 is alsoprovided with a suitable number of vertical pipes 17, the lower ends ofwhich are respectively directed toward the bottom face 13 of the outercasing 11. Further, each of the vertical pipes 17 is provided, at thelower end thereof, with an opening with which a gas nozzle 20 isengaged. Moreover, the bottom face 13 of the outer casing 11 isconnected with the outlet 22 of an air blower 21.

[0028] A cylindrical inner casing 31 having an open top and closedbottom 32 is disposed so as to cover the inner peripheral wall of thepipe burner 15. The cylindrical inner casing 31 is provided, at theportions each facing each flame port 16 of the pipe burner 15, withflame supply ports 33. A gas-permeable porous body 40 having a flatboard-like configuration and made of an aggregate of silicon carbidefiber is disposed at a level of the inner casing 31 which is somewhatbelow where the flame supply ports 33 are disposed. A substantiallyclosed space S is formed between the gas-permeable porous body 40 andthe top plate 12. A metallic rectifying plate 42 provided with a largenumber of holes 41 is disposed below the gas-permeable porous body 40.Further, an exhaust pipe 43 is disposed below the rectifying plate 42 insuch a way that the exhaust pipe 43 is pierced through the peripheralwall of the inner casing 31.

[0029] The top plate 12 functions as a heating surface so that a heatingsubstance 4 such as a pot or a frying pan is permitted to be directlyplaced thereon. The heat resistant glass to be employed as the top plate12 may be any kind of materials which are conventionally known. However,a heat resistant glass imparted with a fine quartz crystalline structureand almost the same degree of thermal expansion coefficient as that ofquartz, is especially preferable. Since the thermal expansioncoefficient of such a heat resistant glass is relatively low, there islittle possibility that the glass can be cracked even if the glass isquenched under a high temperature state thereof as it is heated by aburner. Although the gas-permeable porous body 40 is constituted by asingle-layer structure of the aggregate of silicon carbide fiber in theembodiment shown in FIG. 1, the gas-permeable porous body 40 may beconstituted by a 2-ply structure consisting of an upper layer formed ofthe aggregate of silicon carbide fiber, and a lower layer formed of theaggregate of silica/alumina-based ceramic fiber which is lower inemissivity than the silicon carbide fiber. This 2-ply structure isadvantageous in improving the heating efficiency of gas stove.

[0030] On the occasion of combustion operation of gas stove, apredetermined quantity of fuel gas is fed from the gas nozzle 20 withthe air blower 21 being actuated. The air supplied by this air blower 21to a space between the outer casing 11 and the inner casing 31 ispermitted to flow into the vertical pipe 17 so as to be mixed with fuelgas to form a mixed gas, which is then ejected from the flame ports 16of the pipe burner 15 to form a flame. This flame is then permitted topass through the flame supply ports 33 provided in the inner casing 31and to spread throughout the combustion space S. Part of the air thathas been supplied by the air blower 21 is permitted to enter into thecombustion space S together with the flame ejected from the flame supplyports 33 of the inner casing 31 so as to assist the secondary combustionof flame. As a result, the complete combustion of the mixed gas can bepromoted. The combustion heat produced by the combustion gas isthermally conducted from the top plate 12 to the heating substance 4 tothereby heat the heating substance 4.

[0031] The temperature of the combustion gas generally exceeds over1000° C. As shown by the arrows “A” in FIG. 1, this high-temperaturecombustion gas is permitted to pass through the gas-permeable porousbody 40 and the rectifying plate 42 before it is discharged from theexhaust pipe 43. As this high-temperature combustion gas is permitted topass through the gas-permeable porous body 40, the top surface (thesurface facing the top plate 12) of the gas-permeable porous body 40 isheated up to almost the same temperature as that of the combustion gas.As a result, thermal energy is radiated from the surface of thegas-permeable porous body 40 toward the top plate 12 (as shown by thearrows “B”), thereby providing this radiation energy, through the topplate 12, to the heating substance 4 in addition to the heating by wayof the aforementioned conduction of heat.

[0032] Namely, in the case of gas stove 10 according to the presentinvention, the combustion heat from the burner is transmitted to aheating substance 4 in two ways, i.e. by heat conduction originatingdirectly from the heat resistant glass top plate 12 and by radiant heatproduced from the surface of gas-permeable porous body 40 ashigh-temperature combustion gas passes through the gas-permeable porousbody 40 which is disposed below the top plate 12. As a result, it is nowpossible, even with this type of gas stove where the flame is notpermitted to expose outside, to realize such high heating efficiencythat is sufficiently suited for practical use. It has been confirmed,through the experiments conducted by the present inventors, that the gasstove constructed as described in the above embodiment is capable ofachieving heating efficiency which is comparable to that of theconventional gas stove as shown in FIG. 5 under the same condition withrespect to the input.

[0033] By the way, the gas stove 10 of the above embodiment is providedwith the rectifying plate 42, so that the combustion gas is preventedfrom generating a drift current in the course wherein the combustion gasis transferred from the combustion space S via the gas-permeable porousbody 40 to the exhaust pipe 43. However, this rectifying plate 42 maynot be essential and can be omitted, provided that the drift current ofthe combustion gas can be confined within a tolerable degree through theadjustment of the mounting position or configuration of the exhaust pipe43.

[0034] Further, in the above embodiment, although air for secondarycombustion is utilized in the combustion of burner, the mechanism forintroducing the air for secondary combustion may be omitted, providedthat the complete combustion of gas without substantial unburnt gas canbe achieved by making use of only the primary air and by providing thegas stove with a suitable means such as a flame stabilizing mechanismwhich is conventionally known. In that case, the structure of the gasstove can be more simplified. The outer casing 11 and the inner casing31 may not be circular in horizontal cross-sectional configurationthereof, and hence may be rectangular in horizontal cross-sectionalconfiguration thereof. In that case, the pipe burner may be constructedsuch that it is configured so as to be installed entirely along theinner peripheral wall or to be installed only at a couple of longersidewalls facing each other.

[0035]FIG. 2 shows a cross-sectional view of another embodiment of theflat heating surface type gas stove according to this invention. The gasstove 10A shown in FIG. 2 differs from that shown in FIG. 1 in therespect that the burner is constituted by a surface combustion burner.Namely, the gas stove 10A shown in FIG. 2 is the same as that shown inFIG. 1 in the respect that the open top face of an outer casing 11having a cylindrical configuration is closed by a flat heat resistantglass top plate 12. However, the gas stove 10A is featured in that aninner casing wall 31A is coaxially disposed inside the outer casing 11in such a manner that the circumferential top end of the inner casingwall 31A is not contacted with the top plate 12, and that a ring-shapedcombustion face-forming body 50 is horizontally interposed between theouter peripheral wall of the inner casing wall 31A and the innerperipheral wall of the outer casing 11. Further, the outlet 22 of an airblower 21 is connected with the peripheral wall of the outer casing 11,and the gas nozzle 20 is disposed on an upstream side of the outlet 22.

[0036] The combustion face-forming body 50 may be selected from anykinds of combustion face-forming body that have been employed in theconventional surface combustion burner. In this embodiment however, amaterial exhibiting a high emissivity, such as an aggregate of siliconcarbide fibers (the emissivity thereof is 0.9 or more) is employed.

[0037] As shown in FIG. 2, on the top end of the inner casing wall 31A,there is mounted a disc-shaped gas-permeable porous body 40 which islocated preferably at the same level as that of the combustionface-forming body 50. Although it is not essential, a ring-shapedmetallic rectifying plate 52 provided with a large number of holes 51 isdisposed below the combustion face-forming body 50, and additionally, adisc-shaped metallic rectifying plate 42 provided with a large number ofholes 41 is disposed below the gas-permeable porous body 40. Moreover,an exhaust hole 43A is formed at a region of the bottom 13 of the outercasing 11, which is encircled by the inner casing wall 31A. In the caseof this gas stove 10A, the substantially closed space formed between thegas-permeable porous body 40 and the combustion face-forming body 50functions as a combustion space S. Namely, on the occasion of combustionoperation, when the air blower 21 is actuated and a predeterminedquantity of fuel gas is supplied from the gas nozzle 20, the mixed gasconsisting of the fuel gas and combustion air is permitted to enter intoa space between the outer casing 11 and the inner casing wall 31A, andis stirred and mixed by means of the rectifying plate 52 to form ahomogeneous gas mixture, which is then passed through the combustionface-forming body 50 and ejected therefrom so as to be ignited and burntby a suitable means.

[0038] The combustion heat produced by the combustion gas is thermallyconducted from the top plate 12 to the heating substance 4 to therebyheat the heating substance 4. Additionally, since the combustionface-forming body 50 is formed of an aggregation of silicon carbidefiber exhibiting an excellent emissivity, the heating substance 4 isalso heated by the radiation energy (indicated by the arrows “C”)originating from the surface of the combustion face-forming body 50,thereby making it possible to achieve high heating efficiency. Moreover,as in the case of the gas stove shown in FIG. 1, this high-temperaturecombustion gas is permitted to pass through the gas-permeable porousbody 40 and the rectifying plate 42 before it is discharged from theexhaust hole 43A. During this process, thermal energy is radiated alsofrom the surface of the gas-permeable porous body 40 toward the topplate 12 (as shown by the arrows “Be”), thereby further enhancing theheating efficiency.

[0039]FIG. 3 shows a cross-sectional view of another embodiment of theflat heating surface type gas stove according to this invention. The gasstove 10B shown in FIG. 3 differs, just like the gas stove 10A shown inFIG. 2, from the gas stove 10 shown in FIG. 1 in the respect that theburner is constituted by a surface combustion burner. Furthermore, whilethe gas stove 10A shown in FIG. 2 is featured in that the combustionface of surface combustion burner (the combustion face-forming body 50)is disposed on the outer peripheral side of the gas-permeable porousbody 40, the gas stove 10B shown in FIG. 3 is featured in that thegas-permeable porous body 40 is disposed on the outer peripheral side ofthe combustion face of surface combustion burner (the combustionface-forming body 50). Therefore, the outlet 22 of an air blower 21 isconnected with a region of the bottom 13 of the outer casing 11, whichis encircled by the inner casing wall 31A, and an exhaust hole 33A isformed in the peripheral wall of the outer casing 11.

[0040] The manner of heating to the heating substance 4 on the occasionof combustion operation is substantially the same as in the case of thegas stove 10A shown in FIG. 2, so that the details thereof will beomitted by denoting the corresponding components or members by thecorresponding reference numbers.

[0041]FIG. 4 shows a cross-sectional view of a further embodiment of theflat heating surface type gas stove according to this invention. The gasstove 10C shown in FIG. 4 differs from the gas stove 10B shown in FIG. 3in the respect that a heat exchange is executed between the air beingsupplied for combustion and the combustion gas being discharged. Inother respects, the constitution of gas stove 10C is substantially thesame as that of gas stove 10B shown in FIG. 3, so that the detailsthereof will be omitted by denoting the corresponding components ormembers by the corresponding reference numbers.

[0042] The gas stove 10C shown in FIG. 4 comprises a combustion gaspassageway 62 which is communicated with a combustion gas flow channel61 constituting a downstream side space of the gas-permeable porous body40. This combustion gas passageway 62 is disposed so as to pass, via apartition wall 64, through the interior of a combustion air passageway63 which is connected with the air blower 21. According to the gas stove10C of this embodiment, the quantity of heat retained in the combustiongas after the passage thereof through the gas-permeable porous body 40is transferred via the partition wall 64 functioning as heat-exchangingmeans to the combustion air flowing inside the combustion air passageway63 while the combustion gas passes through the combustion gas passageway62 to thereby perform exhaust heat recovery. As a result, a mixed gasconsisting of the air thus heated up and the fuel gas is enabled to betransferred to the surface combustion burner for the combustion thereof,resulting in further improved heating efficiency as a whole.

[0043] By the way, the aforementioned means for performing the heatexchange between the combustion gas and the combustion air to therebyexecute the exhaust heat recovery can be applied as it is not only tothe gas stove 10B which is provided with the surface combustion burneras shown in FIG. 2, but also to the gas stove 10 which is provided withthe pipe burner as shown in FIG. 1.

[0044] According to the present invention, it is possible to provide anovel flat heating surface type gas stove which is capable of heating aheating substance across a heat resistance glass at high heatingefficiency sufficient for practical use in spite of the fact that thegas stove employs gas as a fuel, thus making it possible to overcome anyinconvenience that may be brought about due to the exposure of flame,and to facilitate the cleaning of the gas stove.

1. A flat heating surface type gas stove comprising; a heat resistanceglass top plate which is disposed over a burner; wherein a gas-permeableporous body is disposed below said top plate, a space between said topplate and a surface of said gas-permeable porous body is assigned to acombustion space, and combustion gas to be generated is designed to bedischarged through said gas-permeable porous body.
 2. The flat heatingsurface type gas stove according to claim 1, wherein said gas-permeableporous body is formed of silicon carbide or a material containingsilicon carbide as a main component.
 3. The flat heating surface typegas stove according to claim 1 or 2, wherein a second gas-permeableporous body having a lower emissivity than that of the first mentionedgas-permeable porous body is laminated on a gas outlet side of the firstmentioned gas-permeable porous body.
 4. The flat heating surface typegas stove according to claim 3, wherein said second gas-permeable porousbody is formed of silica/alumina-based ceramic or a material containingsaid ceramic as a main component.
 5. The flat heating surface type gasstove according to any one of claims 1 to 4, wherein said burner isdisposed around said gas-permeable porous body.
 6. The flat heatingsurface type gas stove according to any one of claims 1 to 5, whereinsaid burner is a surface combustion burner, and a combustion surfacethereof, together with the surface of said gas-permeable porous body, isdisposed to face said combustion space.
 7. The flat heating surface typegas stove according to claim 6, wherein the combustion surface of saidsurface combustion burner is formed of silicon carbide or a materialcontaining silicon carbide as a main component.
 8. The flat heatingsurface type gas stove according to claim 6 or 7, wherein the combustionsurface of said surface combustion burner is placed on the outerperipheral side of the surface of said gas-permeable porous body.
 9. Theflat heating surface type gas stove according to claim 6 or 7, whereinthe surface of said gas-permeable porous body is placed on the outerperipheral side of the combustion surface of said surface combustionburner.
 10. The flat heating surface type gas stove according to any oneof claims 1 to 9, wherein said gas stove further comprises a combustiongas passageway communicated with a space located on a downstream side ofcombustion gas flow channel of gas-permeable porous body; an airpassageway for combustion; and a heat-exchanging means acting betweenthe combustion gas passageway and the air passageway for combustion;wherein a mixed gas comprising a combustion gas and combustion air,which has been heated through heat exchange thereof with the combustiongas by means of said heat-exchanging means is designed to be fed to saidburner.